<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div id="myComputed">
        {{textshow}}
    </div>
    <script src="js/vue.global.js"></script>
    <script>
        const CounterApp = {
            data() {
                return {
                    textData: '123,456'
                }
            },
            computed: {
                textshow() {
                    return this.textData.split(',').reverse().splice(0, 1)
                }
            },
        }
        Vue.createApp(CounterApp).mount('#myComputed')
    </script>
</body>

</html>